On a vanilla amd64-current fresh install, /usr/X11R6/bin/xset seems to be linked to libXfontcache.so.5.0, which I believe was recently dropped from the install sets. This (obviously) makes xset fail on start.
pagurus# xset ld.so: xset: can't load library 'libXfontcache.so.5.0' Killed pagurus# ls /usr/X11R6/lib/libXfontcache.so.5.0 ls: /usr/X11R6/lib/libXfontcache.so.5.0: No such file or directory OpenBSD 6.3-current (GENERIC) #44: Thu May 24 19:18:04 MDT 2018 dera...@amd64.openbsd.org:/usr/src/sys/arch/amd64/compile/GENERIC real mem = 520093696 (496MB) avail mem = 496361472 (473MB) mpath0 at root scsibus0 at mpath0: 256 targets mainbus0 at root bios0 at mainbus0 acpi at bios0 not configured cpu0 at mainbus0: (uniprocessor) cpu0: Intel(R) Core(TM) i7-7700K CPU @ 4.20GHz, 159.86 MHz cpu0: FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,SEP,PGE,MCA,CMOV,PAT,PSE36,CFLUSH,MMX,FXSR,SSE,SSE2,SSE3,PCLMUL,SSSE3,FMA3,CX16,SSE4.1,SSE4.2,MOVBE,POPCNT,AES,XSAVE,AVX,F16C,RDRAND,HV,NXE,PAGE1GB,LONG,LAHF,ABM,3DNOWP,ITSC,FSGSBASE,BMI1,AVX2,SMEP,BMI2,ERMS,RDSEED,ADX,SMAP,CLFLUSHOPT,MELTDOWN cpu0: 256KB 64b/line 8-way L2 cache cpu0: smt 0, core 0, package 0 pvbus0 at mainbus0: OpenBSD pci0 at mainbus0 bus 0 pchb0 at pci0 dev 0 function 0 "OpenBSD VMM Host" rev 0x00 virtio0 at pci0 dev 1 function 0 "Qumranet Virtio RNG" rev 0x00 viornd0 at virtio0 virtio0: irq 3 virtio1 at pci0 dev 2 function 0 "Qumranet Virtio Storage" rev 0x00 vioblk0 at virtio1 scsibus1 at vioblk0: 2 targets sd0 at scsibus1 targ 0 lun 0: <VirtIO, Block Device, > SCSI3 0/direct fixed sd0: 4096MB, 512 bytes/sector, 8388608 sectors virtio1: irq 5 virtio2 at pci0 dev 3 function 0 "Qumranet Virtio Storage" rev 0x00 vioblk1 at virtio2 scsibus2 at vioblk1: 2 targets sd1 at scsibus2 targ 0 lun 0: <VirtIO, Block Device, > SCSI3 0/direct fixed sd1: 360MB, 512 bytes/sector, 738240 sectors virtio2: irq 6 virtio3 at pci0 dev 4 function 0 "Qumranet Virtio Network" rev 0x00 vio0 at virtio3: address 0a:00:10:17:18:92 virtio3: irq 7 virtio4 at pci0 dev 5 function 0 "OpenBSD VMM Control" rev 0x00 vmmci0 at virtio4 virtio4: irq 9 isa0 at mainbus0 isadma0 at isa0 com0 at isa0 port 0x3f8/8 irq 4: ns16450, no fifo com0: console vscsi0 at root scsibus3 at vscsi0: 256 targets softraid0 at root scsibus4 at softraid0: 256 targets root on sd0a (281a39d09c7575bc.a) swap on sd0b dump on sd0b --